1. Technical Field
This document relates to an organic light emitting display device and a driving method of the device.
2. Background Art
An organic light emitting element used for an organic light emitting display device refers to a self-light emitting element in which a light emitting layer is formed between two electrodes on the substrate of the device. Organic light emitting display devices are classified into top-emission type, bottom-emission type, dual-emission type, and so on according to a direction along which light is emitted. Alternatively, organic light emitting devices can be divided into passive matrix type and active matrix type according to a driving method employed.
A sub-pixel disposed in an organic light emitting display panel comprises a transistor unit including a switching transistor, a driving transistor, and a capacitor; and an organic light emitting diode including a lower electrode connected to the driving transistor included in the transistor unit, an organic light emitting layer; and an organic light emitting diode including a upper electrode.
An organic light emitting display panel exhibits light intensity varying in proportion to the amounts of a current flowing through the organic light emitting diode. Since organic light emitting display panels require a large amount of current compared with liquid crystal display panels, in the event of short circuit at power terminals, an excessive amount of current flows into the elements of the respective sub-pixels. Various factors cause short circuit at power terminals, which include not only internal, structural factors such as particles introduced into the organic light emitting display panel during a manufacturing process (or a module process), cracks, misalignment of pad units, and narrow wiring layout but also external factors such as static electricity.
If an excessive current flows into a sub-pixel due to short circuit at power terminals, elements of the corresponding sub-pixel are burnt out. Burning out in a small region may not be perceived at its early stage but neighboring sub-pixels are gradually burnt out as the organic light emitting display panel continues to operate.
In this respect, there are high chances short circuit at power terminals burns out sub-pixels of an organic light emitting display panel and subsequently leads to a fire; therefore, a means for preventing short circuit has to be provided.